dotnet/roslyn

Strange behaviour in async method

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#32,276 建立於 2019年1月9日

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 (5 留言) (0 反應) (0 負責人)C# (20,414 star) (4,257 fork)batch import
Area-InteractiveBugDeveloper CommunityInteractive-Debugginghelp wanted

描述

I have a solution targeting NetCoreApp2.0.

Lately I've seen that when running an async method, the debugger shows me variables that are non allocated (out of scope).

If this variable is an IQueryable<string> it will show show up in the 'Locals window' as NullReferenceException.

If I manually set the 'next statement' to first statement in the block containing this IQueryable<string>, a NullReferenceException will be thrown when accessing the variable.

This issue has been moved from https://developercommunity.visualstudio.com/content/problem/238451/strange-behaviour-in-async-method.html VSTS ticketId: 604787 These are the original issue comments: (no comments) These are the original issue solutions: (no solutions)

貢獻者指南

技術棧
csharp
領域
tooling
議題類型
bug
難度面向新貢獻者的預計實作難度，1 表示很小改動，5 表示專家級工作。
5
預計時間有經驗貢獻者完成調查、實作、測試並準備 pull request 的粗略時間範圍。
over 1 week
活動狀態議題目前的可參與程度：新鮮、活躍、陳舊、阻塞或等待維護者輸入。
stale
清晰度議題是否清楚說明預期改動、驗收標準和下一步。
needs investigation
前置要求
C# async/awaitRoslyn compiler internalsDebugging symbol generation
新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。
15
研究方向
Investigate the async state machine transformation in Roslyn, specifically in the AsyncRewriter class. Look at how local variables are mapped to closures and whether the debugger scoping information is correctly emitted. Check relevant tests for async debugging. No linked PRs found; this issue may require deep analysis of the compiler's code generation for async methods.